In the mid-Atlantic, ground chum is made primarily of menhaden. Farther south, you can find frozen blocks of chum made from Spanish sardines, which are also excellent. Tuna, bonito, little tunny or dolphin carcasses also work well.
Where to Ride the Bag**
Once you have the chum and you're in the ocean, the question becomes where to place the bag. There are several factors to consider. Water temperature is the most important, but water clarity, depth, bottom structure and tide lines all figure into the equation.